This invention relates generally to gas testing devices that are associated with safety and preventive maintenance, and, in particular, is related to a gas leak meter for use in measuring the amount of gas leaking from an underground valve.
For safety reasons, gas pipelines are buried underground up to the point of actual use. Obviously, this involves the use of a great multitude of valves; these valves are normally reached through a valve box that is typically a cylindrical pipe that has an opening on the surface and reaches down to and surrounds the valve.
Because of this valve location and the inability to completely seal the top opening, the valve can be surrounded by water, ice, etc. which leads to rust and eventually leads to a leaking valve.
Past procedures usually involved some person noticing a gas smell in the area and calling a gas line maintenance crew through such agencies as the police and fire department. The gas line crew comes to the site with a leak detector that indicated whether there was a leak or not. If this was answered in the affirmative, the conventional procedure is to replace the valve if the leak was therein.
Although the procedure may sound wise, especially if safety of people and structure is of concern, it may not otherwise be prudent when safety is not the main issue.
For example, if a gas main valve is not in an area of great concern, as noted above, a certain amount of leaking gas may be acceptable. This would depend on the dollar amount of gas leaking in comparison to the replacement cost of the valve. If the cost to replace a valve is $5,000, material and labor, for example, and only $500 of gas is leaking per year, the above procedure involves a excessive investment compared to the problem.
Further, the above procedure does not allow for preventive maintenance other than replacement.
The installation of a typical gas flow meter in the system increases the resistance to gas flow and thus affects the readings. One would desire to have a device which operates at atmospheric pressure and is easily adaptable to a valve box without modification.
These drawbacks have motivated a search for a device that allows one to make a quantity and quality judgment about valve replacement.